To our surprise, there is no significant difference in occurrence of GERD between patients after standard PD (15 of 158 patient) and PPPD (25 of 313 patients, P=0.49). We postulate reflux esophagitis following a PPPD in patients without past history of GERD is most likely caused by disruption of reflux-preventing systems at the gastroesophageal junction, thereby allowing reflux of gastric acid into esophagus. If the postulation is true, GERD after PPPD should be acidic in nature. To test this hypothesis we propose a prospective randomized study to compare preoperative and postoperative parameters, including esophageal morphology, bile acid concentration, trypsin activity of esophageal refluxate, COX2 mRNA expression of lower esophageal mucosa, and 24 hour pH monitor of lower esophagus.